BLACK FOREST High Gain Preamp - Based on the Bogner Uberschall

[J0K3RX]

https://www.youtube.com/watch?v=rM_3h6TnAOA&list=UUUwEIqPJirqqnKe85ggspRQ

Singulano - Great demo!! Good work!

Nice for a change to see somebody make a demo clip!

[JebemMajke]

J0K3RX,
DId Arzone make this layout available? I made your 1590B Triple Wreck and I would love to build this one also.

Cody

Yup! I gots it... Ya want it?

Can I get the arizone Layout as well? And that Triple Wreck would be nice too.

[Darksid]

Prompt scheme 1posta final or have any mod.Zhelayu collect myself ...

[tech9_79]

hey joker could i nab the blackforest layout from ya?

[Singulano]

https://www.youtube.com/watch?v=rM_3h6TnAOA&list=UUUwEIqPJirqqnKe85ggspRQ

Singulano - Great demo!! Good work!

Nice for a change to see somebody make a demo clip!

Thanks man!! Great preamp you did!

[deadastronaut]

slightly of topic sorry jim, , but what string gauge would you guys recommend for drop B on a bog standard guitar

so the lowest isn't flabby?...i just want drop B  to match my 5 string bass..

[JebemMajke]

I can suggest you two types.

Fender 13-65 - baritone, really nice lows, chung chung riffs. The only low point is that the difference between 3rd and 4th string is too big. I used to swap it's 4th string ( 20 ) with something like 27 or 32.

Dean Markley 13-56, really nice low mids, not as much low growl as with fenders, but pretty decent. Way better than just down tuning a 9-42 set.

I had a really bad experience with Zakk Wylde Dunlop set, 10-60, to much mud in the sound ... and the 10.13.17 were really hard to tune correctly

[deadastronaut]

cheers misa, i'll try the 13-56's then as a start off  \m/  \m/

[wgc]

Hey all

I usually hang over at madbean. But here's where I saw this first, and figured it probably belongs here at the least.  Plus I've never really posted in a 50 page thread. Exciting!

here's an smd layout & build I did of the blacker forest. Yes, I spelled vicous wrong.  No, I didn't intend to.  I was just so excited to be laser etching. 

I also etched the tone stack knobs in backwards order.  Ah well.

Mispelling and graphic layout were the least of my challenges on this one.

I did the box ages ago, when I first saw Jim's post elsewhere about the jfet uberschall.  I intended to build it using an etch for through hole parts, but I just never got a good etch.  Time marched on. 

I started doing other things, and recently felt confident enough in my layouts to do an smd version of  his circuit. While I was at it, I decided to combine the boost and the mids mods into one switch so they would come on at the same time for leads.  Went pretty well over all.

Got the pcbs made, and populated, and then it didn't work.  Turns out  that during my layout shenanigans I used a bad pinout on the jfets, but  fortunately, I could just rotate them mismatched to the pads. 

Then it fired up!  And sounded amazing!! 

But the squeal...  dear lord, the squeal, it was heart rending.

I tried all kinds of things.  Shielded cable, cap changes, resistor changes, buffers, etc.  A few things helped but nothing fixed it.  I thought, "maybe I routed those traces too close. Maybe I shouldn't have used a ground plane.  Maybe the ground plane should have only been on one side of the pcb."  All kinds of things went through my head, on multiple nights, at 2am. Or later.

Then while I was in there swapping out caps, I realized I put the treble pot where the bass pot should be.  So I decided to move it and boom.  There it was.

I made this layout to match the box (almost), which I had previously stuffed with pots and a footswitch.  But I never checked the values of the pots once they were in.  Turns out they're from an earlier version of the schematic, not the one I used to do my layout.  Damn it! 

Changed them to match the schem I used for my layout and now most of the oscillation is gone. I still get some at the extremes of vol settings but its so much better...

I might update this pcb (and the box) when I get a chance since there's a few things I'd change now that I'm older and very little wiser, but overall I'm pretty happy with it! 







Awesome job, Jim, love this one!  It sounds killer with a tube screamer at low settings in front of it.

Thanks for looking, have a great weekend...!

[J0K3RX]

It sounds killer with a tube screamer at low settings in front of it. <---  Oh Yeah!

That looks Feckin Awesome duder!!  I have to say that board looks a hell of a lot better than I expected!!   The whole thing looks wicked good!
And now for the drum roll......................................................................Audio Demo

Must tell me more bout the laser etching!? Did you build it...? I have some lasers that I have been playing around with but aside from burning wood and holes in my neighbors siding it hasn't found a useful purpose, yet. 

[wgc]

Ha!  Thx man, great circuit! 

I gotta get a way to record stuff. Too busy building.  But I'll get one up sometime. 

I'm lucky we have a laser at work(not built diy), great fun but also a pita when things don't go well. This was a pretty early one, around page 12 of the thread.  Also we have others who tweak things (not for the better) and I often forget to check.

[J0K3RX]

Billy,

In regards to the unwanted squeal, hiss, hum etc that plague these high gain builds..

Probably nothing you and most others here weren't already aware of but, it really makes me wonder sometimes when I see these pcb circuits jam packed into these tiny enclosures or some of these vero boards that have components scattered all over the place with excessive wires etc... 

Besides the obvious circuit design problems, the pcb layout makes a big difference with noise and that is especially true when it comes to these high gain pedals! Many who have followed this post from the beginning know that I am guilty of this myself and have wasted probably hundreds of needless hours swapping parts and chasing ghosts in my builds...  Live and learn.. Now I am at least aware of it and keep it in mind when I am making a layout.

Quote from "indyguitarist" Brian Wampler:

"I didn't use to believe it, but after testing it myself I found out several years ago that the layout can totally change the feel, sound, and noise level of a circuit.
We experimented quite a bit with layout practices and came across sort of a 'formula' for lack of a better word. Plus, I send my layout guy to some extremely high-dollar courses for EE's that discuss nothing but layout in the audio electronics field. Expensive, but worth it. Sorry I can't give away any tips, but trust me when I say that layout does indeed matter."   

There is plenty of documentation on this subject if you do a google search...

[wgc]

Totally agree- I learned a lot on this one. 

I have my in/out pretty close together on the pcb. Also the ground pour can influence capacitance-I did top and bottom, figured it would help with noise.

But the 3pdt is probably the area that could stand the most improvement.  My std 3pdt wiring puts in/out right next to each other.  In the future, I'd move them to the outside and put the led in the middle. I suspect lots of whine in high gain boxes might be improved by changing the switch wiring.

Aside from all that the biggest improvement was the cap I put in series with r2 at the input. Get rid of the higher freq no one can hear anyway, and there's less of those around to contribute to oscillation.   But it can also change the sound if you're not careful.

I may try changing the volume pot just to see what happens, but for now, I'm leaving it alone.

Anyway, I posted mistakes and all in the interest of helping others avoid or repair similar issues. This is way too cool a circuit to leave in the box of fail..!

[Singulano]

Hi Guys, back here. I´ve made the "Engl 3" of the 14th page and it´s working nice!
Thanks J0K3RX again!
Pretty soon i'll post a test vídeo.
The treble pot was too high for me, so a added a 3-way switch to add another 220p cap or a 470p cap in parallel with the 220p cap in the project. Now I have 3 different voices on the pedal. And the sweep pot, I changed for a trimmer, because don´t seems to be necessary to me always tuning him. 

[J0K3RX]

Hi Guys, back here. I´ve made the "Engl 3" of the 14th page and it´s working nice!
Thanks J0K3RX again!
Pretty soon i'll post a test vídeo.
The treble pot was too high for me, so a added a 3-way switch to add another 220p cap or a 470p cap in parallel with the 220p cap in the project. Now I have 3 different voices on the pedal. And the sweep pot, I changed for a trimmer, because don´t seems to be necessary to me always tuning him. 

Singulano - the Engl is one of my favorites! I have more mods since I posted that... Would like to hear yours!

[Cozybuilder]

Hi Jim- Any chance you will post an updated schematic?

[J0K3RX]

Hi Jim- Any chance you will post an updated schematic?

Perhaps... What did you have in mind?

[Singulano]

This is the box. Soon I'll made a vídeo test, exploring the adjusts.

[slipknot55566618]

I finished assembling the Blackforest today excellent pedal, high gain without excessive distortion , thank J0K3RX

greetings from Brazil 

[Singulano]

Some mods I've done for the Engl 3
Q1= 2N5457
Q5/Q6= 2N5458
Bass pot= 1MA, for better response.
Change the 4n7 cap, that limited the bass, to 22n or other... if increase too much, the sound could tangle.
Change the 220p cap above the treble pot to 370p, to add mid/treble frequency. 220p makes the treble pot add just very high frequencies.(Dimebag fans could like this way)
Soon I have time, I'll post a vídeo test.